Add non-post job/status tracking for Studio social workflows

[chubes4]

Summary

data-machine-socials already tracks some publish history with _dms_shared_posts and exposes GET /datamachine-socials/v1/status/{post_id}.

That works when social publishing begins from a WordPress post, but Studio is starting to operate as a broader internal workspace.

Current State

• Cross-post endpoint can publish to Instagram and other platforms
• Publish history is stored against a WP post when post_id is available
• Status endpoint is keyed to post_id

Gap

Studio workflows are not always guaranteed to start from a WordPress post.
Examples:

• direct social asset uploads
• QR/social utility workflows
• future caption/media prep flows before a WP draft exists
• internal publishing tasks initiated from Studio rather than the post editor

This means current status/history tracking is too post-centric for Studio-driven workflows.

Goal

Introduce a durable status model for social publish operations that does not require a WordPress post ID.

Suggested Direction

• Add a first-class social publish job/history object keyed independently of WP post IDs
• Return a job/status identifier from publish requests
• Support follow-up status polling by job ID
• Continue linking to post IDs when available, but do not require them
• Preserve platform-specific data like media IDs, permalinks, timestamps, and errors

Why This Matters

Studio can already call the socials publish endpoint today, but long-term UX needs better status tracking than post meta tied only to existing WP posts.

This would make socials a better backend for:

• Studio
• future chat-based publishing tools
• internal automation flows
• non-post social workflows